arm64: dts: qcom: sm8250: add watchdog device

Add on-SoC watchdog device node.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20200604004331.669936-7-dmitry.baryshkov@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>